Best JSON Parsers, Viewers and Formatters

JSON is everywhere — it's the default language that browsers and servers use to talk to each other — but raw, minified JSON is painful to read by hand. A good viewer turns a wall of brackets into something you can actually navigate: indentation, syntax highlighting, collapsible nodes, type hints, and validation.

This guide is an updated and expanded round-up of the tools worth knowing in 2026. It's organized by category — online tools, visual graph explorers, browser extensions, Notepad++ plugins, command-line utilities, and desktop apps — and finishes with a feature comparison table. Where a tool from the earlier generation has been renamed, deprecated, or absorbed into another project, that's flagged so you don't waste time chasing a dead link.

Online JSON viewers and formatters

These run entirely in the browser, so there's nothing to install. Most modern ones also process your data locally rather than sending it to a server — worth checking if you handle anything sensitive.

JSON Viewer (stack.hu)

• Link: https://jsonviewer.stack.hu/

A long-running, no-frills viewer that has been online since 2008 and still serves a large monthly audience. Paste your JSON and switch between a raw Text view and a collapsible Viewer (tree) view. It can strip whitespace to minify, re-indent to beautify, and — unlike its early days — it now includes a "Load JSON data" button so you can import a file directly rather than only pasting text. The site keeps nothing on its servers (it doesn't even run a database) and is served over HTTPS.

JSON Editor Online

• Link: https://jsoneditoronline.org/
• Open-source library: https://github.com/josdejong/svelte-jsoneditor (the older library lives at https://github.com/josdejong/jsoneditor)

This is the tool that most "JSON editor" clones are copied from, and it has grown well beyond a simple viewer. It offers three side-by-side modes — code, tree, and table — and lets you format, repair broken JSON, validate against a JSON Schema, compare two documents on a data level (ignoring whitespace and key order), and run queries to filter and transform data. Query support has expanded over the years and now includes JSON Query, JMESPath, and JSONPath-Plus. It handles files up to 512 MB, ships light and dark themes, and is genuinely an editor — you can change values and save your work. Built and maintained by Jos de Jong.

JSON Parser Online

• Link: http://json.parser.online.fr/

A compact, focused parser (hosted on a French domain) that's good at folding and unfolding the document structure. Alongside the tree, it shows JSON types, evaluates the data, and reports how many elements are present, including array indexes — handy when you're trying to understand the shape of an unfamiliar payload rather than edit it. It also ships with sample documents, including a deliberately invalid one, which makes it a nice teaching tool.

JSONLint

• Link: https://jsonlint.com/

The best-known dedicated validator. Paste your JSON, click validate, and it pinpoints syntax errors with line references, then pretty-prints the result if it's valid. Reach for this when your concern is "is this even legal JSON?" rather than browsing structure.

JSON Formatter & Validator (Curious Concept)

• Link: https://jsonformatter.curiousconcept.com/

A clean formatter-plus-validator that lets you choose which JSON specification to validate against (RFC 8259, ECMA-404, and others) and offers configurable indentation. A solid middle ground between a pure validator and a full editor.

Note on older "image-preview" viewers: some first-generation online viewers advertised a quirk where image URLs sitting inside string fields were rendered as thumbnails. That behaviour was never standardized and the tools that offered it have largely gone offline. None of the actively maintained viewers above depend on it.

Visual / graph-based explorers

A newer generation of tools renders JSON as an interactive diagram instead of an indented tree. These shine when a document is deeply nested and you want to grasp its shape at a glance.

JSON Crack

• Link: https://jsoncrack.com/
• Source: https://github.com/AykutSarac/jsoncrack.com

Open-source and free, JSON Crack turns your data into an interactive node graph (or a tree) as you type. It also handles YAML, CSV, and XML, converts between formats, validates, runs jq and JSON Path queries, generates types (TypeScript interfaces, Go structs, Rust serde, JSON Schema, and more), and exports the diagram as PNG, JPEG, or SVG. Processing happens in your browser, and there are official VS Code and Chrome extensions.

JSON Hero

• Link: https://jsonhero.io/
• Source: https://github.com/triggerdotdev/jsonhero-web

A polished, readable explorer from the Trigger.dev team. Rather than a graph, it gives you switchable column, tree, and editor layouts, and it's smart about recognizing values — it previews images, colors, and dates inline. Open source, so you can self-host it.

Browser extensions

Browsers handle JSON inconsistently: Firefox has shipped a built-in JSON viewer since version 53 (2017), while Chrome still prompts you to download or shows raw text by default. So a good extension matters more on Chromium-based browsers than on Firefox.

JSONView (Firefox & Chrome)

• Firefox: https://addons.mozilla.org/en-US/firefox/addon/jsonview/
• Chrome: install "JSONView" by Ben Hollis from the Chrome Web Store
• Source: https://github.com/bhollis/jsonview
• Project site: https://jsonview.com/

The classic. When you open a URL that returns application/json, JSONView formats it in place with syntax highlighting and collapsible arrays and objects, and still shows the raw text if the document is malformed. It's now a single cross-browser WebExtension maintained by Ben Hollis, with high user ratings. (Its original home on Google Code closed when that service shut down; development moved to GitHub.)

Deprecated: the separate jamiew/jsonview-chrome port is officially marked deprecated on GitHub — install Ben Hollis's cross-browser JSONView instead.

JsonDiscovery (Firefox & Chrome)

• Firefox: https://addons.mozilla.org/en-US/firefox/addon/jsondiscovery/
• Source: https://github.com/discoveryjs/browser-extension-json-discovery

A more powerful alternative built on the Discovery.js engine. It shows JSON as an interactive tree, derives a TypeScript-like signature of the data, and lets you run queries with the Jora language and share reports by link. Works on local files and offline.

Tip: several Firefox extensions (JsonDiscovery, Virtual Json Viewer, JSON Lite) require you to first disable the native viewer at about:config by setting devtools.jsonview.enabled to false.

Notepad++ plugins

If you live in Notepad++, two plugins cover almost everything. Note that the old Plugin Manager was replaced by the built-in Plugins Admin in Notepad++ 7.6 — that's where you install these now (Plugins → Plugins Admin → search).

JSON Viewer

• Source: https://github.com/kapilratnani/JSON-Viewer

Adds a dockable tree panel that renders your current JSON file as expandable nodes; selecting a node highlights the corresponding text in the editor. Good for navigating structure inside a large file without endless scrolling.

JSTool (formerly JSMinNpp)

• Project site: https://www.sunjw.us/jstool/npp/
• Source: https://github.com/sunjw/jstoolnpp
• Downloads: https://sourceforge.net/projects/jsminnpp/

This is the modern, actively maintained successor to the old JSMin plugin — it was renamed from JSMinNpp to JSTool. It formats and minifies JavaScript and JSON (the format shortcut is Ctrl+Alt+M), sorts JSON keys alphabetically, and includes its own JSON tree viewer that handles 10 MB+ files comfortably. There's also a Visual Studio Code edition. In other words, the two separate Notepad++ tools from the old days — a structure viewer and a minifier — are now effectively combined here.

Worth adding for completeness: JSLint (validation) and XML Tools (whose pretty-print also works on JSON) are commonly paired with the two above.

Command-line tools and libraries

When you need to script, automate, or process JSON in a pipeline rather than just look at it, move to the terminal.

jq

• Link: https://jqlang.github.io/jq/
• Source: https://github.com/jqlang/jq

The de facto standard command-line JSON processor. It pretty-prints, filters, reshapes, and queries JSON with a concise, expressive language, and it's available on every major platform. Indispensable for working with API responses in shell scripts.

jsonrepair

• Link / source: https://github.com/josdejong/jsonrepair

A library (and CLI) that fixes common JSON problems automatically — trailing commas, missing quotes, comments, and so on. It's the engine behind the repair feature in JSON Editor Online and is easy to drop into your own tooling.

Desktop applications

For very large files or offline work, a native app beats a browser tab.

Dadroit JSON Viewer

• Link: https://dadroit.com/

A desktop viewer engineered for huge files — it can open multi-gigabyte JSON quickly, with fast search and a tree view, where browser-based tools choke. Available for Windows, macOS, and Linux.

DevToys

• Link: https://devtoys.app/

A "Swiss-army knife for developers" that runs entirely offline. Among its many utilities are a JSON formatter, a JSON-to-YAML converter, and validators — useful when you don't want to paste data into a website at all.

Feature comparison

How to choose

• Quick paste-and-read? JSON Viewer (stack.hu) or, on Firefox, the built-in viewer.
• Edit, compare, or query in the browser? JSON Editor Online.
• Understand a tangled, deeply nested document? JSON Crack or JSON Hero.
• Inspect API responses in your browser? JSONView (essential on Chrome) or JsonDiscovery.
• Working in Notepad++? JSTool plus the JSON Viewer plugin.
• Automating or scripting? jq, with jsonrepair to clean up messy input.
• Massive files or offline-only? Dadroit JSON Viewer or DevToys.

One habit worth keeping regardless of tool: when JSON contains anything sensitive, prefer tools that explicitly process data in your browser (or run locally) rather than uploading it to a server you don't control.